Voltage-gated potassium channel antibody limbic encephalitis: a case illustrating the neuropsychiatric and PET/CT features with clinical and imaging follow-up.

OBJECTIVE: To illustrate the neuropsychiatric and imaging findings in a confirmed case of voltage-gated potassium channel antibody limbic encephalitis. METHOD: Case report and review of the literature. RESULTS: A 64-year-old man presented with several months' history of obsessive thoughts and compulsions associated with faciobrachial dystonic seizures. He had no significant past medical and psychiatric history. Physical examinations revealed only mildly increased tone in the left upper limb. Bedside cognitive testing was normal. Positron-emission tomography showed intense symmetrical uptake in the corpus striatum. No underlying malignancy was identified on whole body imaging. Magnetic resonance imaging, lumbar puncture and electroencephalogram were normal. Serum voltage-gated potassium channel antibodies were strongly positive. The patient had a favourable response to antiepileptic drugs, oral steroids and immunotherapy. CONCLUSIONS: Voltage-gated potassium channel limbic encephalitis characteristically presents with neuropsychiatric symptoms and temporal lobe seizures. Positron-emission tomography-computed tomography can be a useful adjunct to the clinical and biochemical work-up.

Primary lateral sclerosis-like picture in a patient with a remote history of anti-N-methyl-D- aspartate receptor (anti-NMDAR) antibody encephalitis.

Anti-N-methyl-D-aspartate receptor (anti-NMDAR) encephalitis is a well-recognised disorder, first fully characterised in 2007. The long-term sequelae reported thus far include relapses with typical, as well as partial aspects of the well-defined neuropsychiatric syndrome. Rarely, isolated atypical symptoms (diplopia, ataxia and tremor) have been reported as relapse phenomenon. We report a case of a patient with a remote history of likely anti-NMDAR encephalitis with the longest follow-up reported in the literature to date (22 years). The relapse presentation was of a purely upper motor neuron syndrome with a primary lateral sclerosis-like picture.

Progressive myopathy with up-regulation of MHC-I associated with statin therapy.

Statins can cause a necrotizing myopathy and hyperCKaemia which is reversible on cessation of the drug. What is less well known is a phenomenon whereby statins may induce a myopathy, which persists or may progress after stopping the drug. We investigated the muscle pathology in 8 such cases. All had myofibre necrosis but only 3 had an inflammatory infiltrate. In all cases there was diffuse or multifocal up-regulation of MHC-I expression even in non-necrotic fibres. Progressive improvement occurred in 7 cases after commencement of prednisolone and methotrexate, and in one case spontaneously. These observations suggest that statins may initiate an immune-mediated myopathy that persists after withdrawal of the drug and responds to immunosuppressive therapy. The mechanism of this myopathy is uncertain but may involve the induction by statins of an endoplasmic reticulum stress response with associated up-regulation of MHC-I expression and antigen presentation by muscle fibres.